Electric circuit breaker



Oct. 8, 1935. w. A CQATES 2,016,893

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William A. Coate Patented Oct. 8, 1935 UNITED STATES ELECTRIC CIRCUIT BREAKER William A. Coates, Bowdon, England, assignor to General Electric Company, a corporation of New York Application April 5,

1935, Serial No. 14,949

In Great Britain April 23, 1934 7 Claims.

This invention relates to electric circuit breakers of the explosion pot type in which the contacts provide two breaks in series, one of which is known as a pressure generating or blast-producing break and the other the main break.

In circuit breakers of this type the pressure generating break occurs between a fixed contact and an auxiliary contact in a reservoir chamber wherein pressure is generated by the resulting are causing the oil, or other suitable arc-extinguishing insulating liquid, to flow from said reservoir chamber through one or more oil ducts to extinguish the are at the main break in another chamber or pot. This chamber is separated from the reservoir chamber by a perforated partition.

Alternatively, the pressure may direct said liquid through said oil duct, or ducts, to cross passages formed in an insulating member, the cross passages being associated with the reservoir chamber through a longitudinal channel.

The main arc is formed between said auxiliary contact and the receding main moving contact, the auxiliary contact providing a conducting ate or door or other closure between the reser- 5 voir chamber and the aforesaid partition perforation or longitudinal channel for ensuring that upon opening the contacts the oil or other liquid flows from the reservoir chamber to the main are through the oil ducts rather than directly through 30 the perforation or transverse channel.

In circuit breakers of the kind above specified, the aforesaid closure has heretofore been obtained either by arranging the auxiliary contact so as to fill at all times the perforation or channel at the place where it enters the reservoir chamber in which case the main moving contact never enters the reservoir chamber, or by arranging the auxiliary contact as a hinged door or gate which is opened against spring pressure by the main moving contact when it enters the reservoir chamber to engage the main fixed contact therein. It will be appreciatedthat such springs may be a source of weakness not only from the mechanical aspect but also because their accommodation may weaken the insulation.

A principal object of the present invention is the provision of an improved construction or .arrangement in circuit breakers of the aforesaid type permitting elimination of springs connected with the intermediate or auxiliary contact acting as a door or gate which is opened and closed when the main moving contact enters and leaves the reservoir chamber respectively.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, Fig. 1 is an eleva- 5 tional view, partly in section, of electric circuit breaker construction embodying my invention, and Fig. 2 is a similar view showing another form my invention may assume.

Referring to Fig. 1 of the drawing which illustrates the explosion pot and contact arrangement of one pole of an oil circuit breaker, I represents the main moving contact in the form of a rod or plug, and 2 the fixed contact which will usually be of the split socket or multiple spring finger type as indicated in the drawing, wherein but one of such fingers or socket segments is visible. Said fixed contact 2 is housed in a reservoir chamber 3 which is normally full of oil or other insulating liquid and in which the first of the two series arcs is drawn, so that the pressure resulting from the are drawn in this chamber. causes the liquid therein to flow therefrom through one or more ducts 4 through transverse passages 5 in an insulating member 6. These passages open into the surrounding oil body at their ends which are remote from duct 4, namely at the right-hand side in the figures.

In an alternative well known arrangement to which the present invention is equally applicable, an explosion pot having an exhaust opening only at the lower end through which the rod contact I operates forms the upper and lower chambers above referred to.

According to the invention the door or gate is arranged so that it normally closes by gravity and a resilient contact finger is provided and so located in the reservoir chamberas to be engaged and deflected from its normal position by the door or gate only when the latter is moved 40 from its closed position upon the entry of the main moving contact into the reservoir chamber to engage the main fixed contact with which said resilient contact finger is in electrical connection, and the arrangement is such that when the main moving contact is withdrawn for opening the circuit breaker the resilient contact finger gives the door or gate an initial bias towards the closed position. This causes a first or pres-- cure generating are to strike between the resilient finger and the door or gate which is of metal and which remains in engagement with the main moving contact until the latter leaves the reservoir chamber and permits the door or gate to close fully by gravity assisted by the presthe entry opening 9 into the reservoir chamber 3 for the moving contact I is adapted to be closed by a conducting gate or door such as the metal flap I which is freely hinged at II in a recess I2 in the upper face of the portion 6a of the insulating block or explosion pot 6. Carried from the mounting I3 of the fixed contact 2 is a resilient conducting finger having an arcing tip I so arranged that neither the finger nor its tip is engaged at any time by the moving contact I. The disposition of said finger l4 and tip I5 is further such that when the moving contact I enters through the perforation 9 the fiap I0 is opened and then engages the arcing tip I5 and deflects the latter with the finger I4.

Furthermore, when the main moving contact 'I is withdrawn on opening the circuit breaker the flap III on being released from the contact I is given an initial bias by the spring finger I4 towards the closed position which said flap normally occupies due'to gravity. The first arc is thus struck in the reservoir chamber 3 between arcing tip I5 and the flap I0 and the resulting pressure in the chamber 3 assists in the closure oi! the flap Ill. The second arc is struck in the longitudinal passage 90 in the insulating block 6, or in the alternative arrangement this second arc is struck in the second chamber or explosion pot 8. This are is drawn between the lower side 01 the fiap III and the upper end 0! the receiving moving contact I.

In carrying out the invention the door or gate may be either in the form or a ball operating in an inclined recess in the insulating floor o! the reservoir chamber so as to be deflected laterally and upwards to engage the spring contact finger when the main moving contact enters the reservoir chamber, or the door or, gate may be in the form or a hinged flap lying when closed horizontally in a recess in the aforesaid floor.

The arrangement shown in Fig. 2 diners only from that shown in Fig. 1 in that the flap I0 is replaced by a conducting ball Ina which is adapted to seat by gravity in a recess IS in the upper face or the insulating part id as indicated by the dotted circle. The arrangement is such that the ball is moved along an inclined recess I! to the illustrated full line position wherein the spring finger I4 is engaged by the same and deflected.

It will be noted in connection with the above described arrangements that arcing within the chamber 3 is confined to the arcing tip I5 and the conducting door or gate III which constitutes the auxiliary or intermediate contact. Accord-' ingly, the main current-carrying portions of the fixed contact 2 are not subject to burning or oxidation by arcing. Likewise, in the circuit closing operation the circuit'is first completed through the intermediate contact and the resiliently mounted arcing contact so that burn ing or the fixed contact proper is also precluded when the breaker is closed on heavy currents.

It will likewise be noted that the pressure generating arc in thechamber 3 is formed only when it is about to be needed, that is immediately prior to closing of the conducting gate, accompanied by the complete withdrawal of the movable contact from the chamber 3. The arc pressure in the chamber 3 serves not only to bias the gate closed after the initial bias by the resilient arcing portion I 4, but also positively to seat the conducting gate over the central passage 9.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may ocur to one skilled in the art without departing from the spirit or my invention.

What I claim as new and desire to secure by Letters Patent in the United States is:

1. An electric circuit breaker of the explosion chamber type comprising relatively movable contact structure arranged to form two arcs in series, said contacts including a relatively fixed contact, a movable contact, and an auxiliary contact, and an arcing contact electrically connected to said fixed contact, said movable contact arranged to move said auxiliary contact into engagement with said arcing contact prior to engagement 0! said movable and fixed contacts.

2. An electric circuit breaker of the explosion chamber type comprising relatively movable contact structure arranged to form two arcs in series, said contact structure including a movable conducting member for directing pressure generated by one of said arcs, and means electrically connected to and resiliently mounted with respect to said contact structure independently of said conducting member tending to bias said member towards its pressure directing position on circuit opening movement of said contact structure.

3. An electric circuit breaker of the explosion chamber type comprising a'fixed contact and a movable rod contact coacting with an explosion pot, means forming a plurality of chambers in said pot, said rod contact operable through said chambers, a conducting member arranged to move into the path of said movable contact upon circuit opening movement of said contact so as to close an opening between two of said chambers, and a resilient arcing contact electrically connected to said fixed contact arranged to engage said conducting member in the closed circuit position and bias said member towards a position closing said opening.

4. An electric circuit breaker of the explosion chamber type comprising a fixed contact and a movable contact arranged directly to engage said fixed contact, a conducting gate member arranged to be interposed between said fixed and movable contacts in the circuit opening operation so as to form two arcs in series, and a resil iently mounted arcing contact electrically connected to said fixed contact arranged to engage said conducting gate in the closed circuit position and to bias said gate towards said interposing position when said fixed and movable contacts are separated.

5. An electric circuit breaker of the explosion chamber type comprising a fixed contact, a movable contact arranged directly to engage therewith, a conducting ball arranged to be interposed in the path of said movable contact for forming two arcs in series between said fixed and movable contacts in the circuit opening operation, and a resiliently mounted arcing contact electrically connected to said fixed contact arranged to engage and bias said ball towards said interposed position, separation of said fixed and movable contacts being followed by separation of said conducting ball and arcing contact so as to form therebetween one 0! said series arcs.

6. An electric circuit breaker of the explosion chamber type comprising relatively movable contacts separable within a pressure confining chamher, one of said contacts operable through a wall of said chamber, a conducting gate member arranged to close the contact opening in said wall during the circuit opening operation so as to form two arcs in series, and means for imparting a closing bias to said gate member only during the initial closing movement thereof, the pressure generated in said chamber by arcing serving com pletely to close said gate member when the afore said contact is withdrawn from said chamber.

7. An electric circuit breaker o! the explosion chamber type comprising relatively fixed and movable contacts arranged to be in direct engagement in the closed circuit position, an auxiliary contact arranged to be interposed between said fixed and movable contacts during opening of the circuit forming two arcs in series, and an arcing contact electrically connected to and forming a part of said fixed contact, said movable contact arranged to bias said auxiliary contact into engagement with said arcing contact, said arcing, auxiliary and movable contacts maintaining the circuit subsequent to separation of said fixed and movable contacts so that arcing is initiated between said arcing and auxiliary contacts.

WHJLIAM A. COATES. 

